The p75 TNF-α receptor is critical for TNF-α–induced E-selectin, VCAM-1, and ICAM-1 expression on mouse ECs. Quantification of E-selectin (A), VCAM-1 (B), and ICAM-1 (C) on the mouse endothelial cell surface. Biotin-conjugated primary antibodies and the [¹²⁵I]-streptavidin system, as described in “Materials and methods,” were used to determine surface expression of E-selectin, VCAM-1, and ICAM-1 on untreated or TNF-α–treated (mouse TNF-α, 3 hours) cultured mouse aortic ECs isolated from WT, p75^−/−, or p55^−/− mice. (D) Mouse cremaster muscles treated with mouse TNF-α (3 hours) or vehicle (PBS) were dissected and frozen using OCT. Cryostat sections were immunostained for ICAM-1 as described in “Materials and methods.” Arrowheads show ICAM-1–stained ECs. (E) Cultured WT mouse aortic ECs were treated with mouse TNF-α (2 ng/mL, ▪) or human TNF-α (2 ng/mL, □) and after 2 hours total RNA was isolated and real-time PCR was performed as described in “Materials and methods.” Values are expressed as fold induction with respect to controls. Error bars indicate SD.